# Systemic Bacillus Calmette-Guérin (BCG) Infection in a Patient With Non-Muscle-Invasive Bladder Cancer: A Case Report

## TL;DR

A patient with bladder cancer developed a rare systemic BCG infection after treatment, highlighting the need for early diagnosis and proper care.

## Contribution

This case report highlights the rare but severe complication of systemic BCG infection following standard bladder cancer therapy.

## Key findings

- Systemic BCG infection can occur despite a normal immune system and may initially be misdiagnosed.
- Antituberculosis treatment successfully resolved the infection after proper diagnosis.
- Persistent fever without an obvious source should prompt consideration of BCG infection in treated patients.

## Abstract

Intravesical Bacillus Calmette-Guérin (BCG) instillation is a widely used adjuvant therapy for non-muscle-invasive bladder cancer (NMIBC), typically associated with a favorable safety profile. However, severe complications such as systemic BCG infection, though rare, can occur and are potentially life-threatening. Diagnosing systemic BCG infection is challenging due to frequently negative microbiological results. We report the case of a 67-year-old immunocompetent man who developed a systemic BCG infection after undergoing BCG therapy for NMIBC. Initially misdiagnosed as a urinary tract infection, his condition worsened despite antibiotic treatment. The diagnosis of BCG sepsis was suspected after prolonged fever, asthenia, and other systemic symptoms. Prompt initiation of antituberculosis treatment with rifampicin, ethambutol, and isoniazid led to a full recovery. This case underscores the critical importance of early recognition and treatment of systemic BCG infections, particularly in patients presenting with persistent fever and no clear source of infection.